I'm running the 5-Aug-2014 version Debian. If /etc/dogtag doesn't exist, or is older than shown here, you need to update your image.

Updating your SD image

The Bone can boot from either the built in eMMC (either 2G or 4G depending on which version of BeagleBone Black you have), or from the micro SD card. For this class we'll be booting from the SD card. It's faster to flash, and if you mess up something it's easier and quicker to recover.